1. Field of the Invention
The present invention relates generally to a method of adapting and repurposing used, spoiled, or excess thermal window glass units that would normally go to waste, into inexpensive new thermal solar energy collecting panels for the purpose of generating product hot water or for other heating or energy generation purposes.
2. Description of the Related Art
Thermally insulated dual pane windows have been used in new construction and remodeling for some years now. Typically, building codes mandate the use of such windows to reduce energy loss from homes and other buildings. Conditioning of air with fossil energy, whether the air is heated or cooled, can be wasted through contact with highly thermally conductive glass doors and windows. Heated air inside will be cooled due to cooler temperatures outside of a building, the heat energy being transferred conductively through cold glass windows and doors. Similarly, cooled air inside will be heated by contact with warmer glass exposed to hot temperatures outside. This temperature loss in buildings is typically most pronounced at windows and doors as walls are easier to insulate than openings. In the past, windows and sliding glass doors were single-pane glass, with a very low thermal resistance value (R value). Untreated glass is a good conductor of heat energy. Thermally insulated windows and glass doors improve the R value significantly and save a considerable amount of heating and cooling energy compared to single pane windows and sliding glass doors over the useful life of a building.
Glass “E” coatings can be applied in the manufacturing process to different faces of thermal window glass to increase their insulation effectiveness. These coatings can be designed to either reflect or absorb long-wave solar radiation, depending on the window design and the desired results. Reflecting thermal solar radiation will help to keep the interior of a structure cooler in the summer, while absorbing solar radiation will help to keep the interior warmer in the winter.
Thermal windows are formed by holding two or more panes of glass in a frame in way that they do not touch each other, thus avoiding conduction of heat energy from one glass pane to the other. The gap between the panes of glass is filled with a gas for increasing the thermal insulation of the window panes from each other. These spaces are sealed air-tight along the perimeter edges of the glass panes with a rubber like seal or gasket. In practice, the glass portions of thermal windows are often referred to in the industry and in this document as “Insulated Glass Units” or “IGUs.” IGUs come in many dimensions from many manufacturing firms. An IGU held in a frame is an insulated window or insulated sliding glass door.
IGUs are limited to a useful lifespan of approximately twenty years. As the IGU ages, humid air enters the space between the window panes as the rubber gasket deteriorates and barometric pressure varies, resulting in a pumping effect. Higher atmospheric pressure squeezes the glass panes together, and lower atmospheric pressure relaxes the squeeze effect creating a partial vacuum, thus “pumping” humid atmospheric gas into the space between the glass panes through tiny leaks in the seal. Humidity within the space between the glass panes can build up, causing water to condense on the inner glass surfaces. Sodium bentonite granule packets or similar water absorbing materials may be hidden in the window frame of higher-grade IGUs to absorb such atmospheric humidity. This dehumidifying effect lasts until the water absorption material reaches its maximum water holding capacity. The trapped humid air eventually creates a fog which condenses on the sealed interior glass surfaces. This creates an unsightly foggy deposit that is quite visible, unattractive, and nearly impossible and extremely uneconomical to clean and correct. Additional wasted IGUs are a result of updating structures with newer, more efficient thermal window units.
Although it is theoretically possible to disassemble the thermal window, remove the rubber gasket, separate and clean the glass panes and reform the IGU with fresh gasket materials, such efforts are laborious and mechanically difficult and thus economically ineffective. It is difficult to adequately clean the interior glass surfaces, (which develops a well attached lime like deposit) install a fresh, functional gasket, re-introduce inert gas between the panes, while at the same time fully remove potentially humid air. Without the proper working conditions and equipment, this becomes an impractical exercise. While some procedures to clean the IGUs have even been patented, the practical solution in the glass industry remains removing and disposing of the old IGU and replacing it with a new IGU. Even when IGUs are disassembled and cleaned, such cleaning procedures are not always successful and the deterioration of the gasket is generally not addressed by cleaning procedures.
The result is that many spoiled IGUs with fog and/or lime deposits on the interior surfaces between the panes of glass are normally wasted and replaced with new IGUs. Even recycling the used glass in old IGUs by melting them down is frustrated due to contamination of such glass by the well attached rubber gasket, which is very hard to fully remove and the “E” coatings on the glass are also considered contaminants. Bits of rubber gasket contamination in a large batch of molten glass spoils the entire batch for most uses. Consequently, most IGUs are discarded. Glass industry experts project that as many as 10,000,000 used IGUs are discarded every year in the United States. Discarding used glass units also wastes the energy it takes to replace them. Even melting used glass down and re-using it as molten glass only saves about 50% of the energy required to cast new glass and is problematic as stated above. Adding to the mass of spoiled and used IGU introduced to the landfills are older, functioning IGUs which are being replaced with more modern or more efficient windows by the window replacement industry.
Thermal solar panels used to heat domestic water consist of a glass cover plate, a thermal collector plate, a fluid circulation channel attached to the collector plate, an encompassing frame and gaskets to hold the panel parts together and typically, insulation behind the solar panel to prevent thermal losses through the back of the panel that would otherwise be captured by the collector. Thermal solar panels trap and transform long wave heat energy from the sun into useable hot water. Thermal solar panels are at the forefront when considering economic renewable energy sources and sustainable building practices. Using thermal solar panels to decrease the required heat energy that is consumed in a building, without relying on the burning of limited fossil fuels, is a step towards reducing carbon emissions and eliminating energy waste.
Solar panels operate by absorbing long wave heat energy in the sun's rays. To do this, a solar panel generally employs a flat or matt textured dark substance as a collector plate which is better suited for absorbing solar radiation than a light-colored, reflective substance. Thermal solar panels can be made of any heat conducting dark substance.
A typical solar hot water installation, often referred to as a “thermal solar system”, uses heat energy from the sun to heat a fluid, which is in turn used to move heat collected in the panel array to be concentrated in a fluid heat storage vessel or tank. The process involves progressively heating a body of water in a hot water tank. Solar hot water panels are installed on the rooftop or other suitable location with access to direct sunlight. Each panel contains a dark colored absorber plate complete with fluid circulation means in conductive contact with the plate. Thermal Solar systems commonly provide supplemental heat as the water tanks used for storage of the product hot water are typically electric or gas heaters to provide hot water at all times. Solar panels can't collect heat energy without direct access to sunlight, and so the thermal solar system heats the water when sunlight is available, and the electric or gas system heats the water when sunlight is absent. Thermal solar heat energy collected from panels may be used to heat hot water, heat air, heat a building slab for radiant heating or other purposes.
The fluid circulation loop means includes a pipe system running from the storage tank to the panels and back from the panels to carry the heated water or heated thermally conductive fluid from the solar panel array to a place where it can be stored or used. Hotter water from the solar array tends to rise to the top of the storage tank and cooler water tends to sink to the bottom of the storage tank. Cooler water from the bottom of the tank is sent to the solar array. This effect of convection in the water column tends to concentrate heat energy. A small electrical circulation pump controlled by an electronic differential controller powers the circulation loop that concentrates the heat. A heat exchanger may be employed in the loop to transfer heat from the hot circulating thermal fluid, such as glycol/water or oil and then circulate the cooled thermal fluid back to the solar hot water array to be reheated. The product hot water is in conductive contact with surfaces in the heat exchanger and is thus progressively heated. The use of a heat exchanger is advantageous during freezing weather because a glycol/water fluid is less susceptible to freezing, whereas product tap water might freeze within the panels, causing it to burst due to expansion. However, any transfer of heat across a heat exchanger will slightly lower the efficiency of the system, and this loss of efficiency must be taken into account.
Food grade glycol with positively charged carbon in suspension may be a heat absorbing member or collector plate of a solar panel. Food grade corn Glycol offers advantages in case a leak in the heat exchanger allows some glycol to enter the potable water. A person who accidentally ingests diluted food grade glycol will not suffer injury as might occur with regular glycol. Anti-freeze as the heat absorption fluid protects the panels from damage in freezing weather but slightly reduces the effectiveness of plain water. Oils may also be used for the thermally conductive fluid in a thermal solar installation.
The loop cycle of heating the fluid, thermal energy extraction, and sending the cooler fluid back to absorb more heat energy is begun anew with each sunrise and lasts throughout the solar day for the effective life of the thermal solar hot water system. A heat sensor on the panel array is wired to operate the electrical differential controller device used to turn off the electrical circulation pump when the sun goes down or when the heat in the tank exceeds the temperature of the panel array. Alternatively, a small photovoltaic solar panel may be used to power the fluid circulation pump when solar energy is available.
It would be economically and environmentally advantageous to make good use of previously unusable spoiled IGUs currently being placed in landfills by converting them into inexpensive solar energy collecting panels. Heretofore, there has not been a method described like the one presented here.